Compositions containing poly(phenylene ether)s and styrenic block copolymers are known and valued for their improved properties relative to either resin type alone. For example, U.S. Pat. No. 3,660,531 to Lauchlan et al. describes blends of “polyphenylene oxide resin” with styrene-butadiene block copolymers and teaches that the blends exhibit a useful combination of low-temperature melt processability, high impact strength, and high flexural strength. As another example, U.S. Pat. No. 5,234,994 to Shiraki et al. describes blends of a “polyphenylene ether”, a polystyrene, and a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene. The blends are described as offering improved transparency, impact resistance, surface hardness, heat resistance, and gloss. As yet another example, U.S. Pat. No. 6,274,670 to Adedeji et al. describes blends of a “polyphenylene ether resin”, a non-elastomeric styrenic resin, and an unsaturated elastomeric styrenic block copolymer. When the non-elastomeric styrenic resin is a styrene-butadiene block copolymer having at least 50 weight percent styrene, the compositions are semi-transparent and exhibit enhanced processability.
Despite these advances, there remains a need for poly(phenylene ether) compositions that exhibit improved heat resistance and notched Izod impact strength while substantially maintaining optical properties. There is also a particular need for such compositions to be free of flame retardants, such as organophosphate esters, that would discourage their use in the food packaging, food service, and healthcare industries.